Count by weight machines, for both banknotes and coins, have existed for many years and are in use in banks and retailers all over the world. Accurate and successful counting depends on evaluating note and coin weights under varying conditions. This means not only where there are no air movements but also under non-standard conditions, for example where there may be air currents from fans and air conditioning equipment.
Normally a scale pan or hod, used to collect notes or coins (and indeed even the currency itself by virtue of its surface area), can cause variations in the measured weights and the effect of these air currents causes errors in the measured weights. The effect of these transients slow down evaluation of interpreted weights and even cause errors in the final interpreted weight and computed value making the weigh counting device unreliable or at worst useless.
Traditionally it has been possible to reduce these effects with streamlining or improving the aerodynamics of the weighing system or providing a shield or shroud to enclose the count by weight machine.
The slowing down and inaccuracy caused has long been an operational problem and on the whole has only been resolved by moving the machine to a location where the effect of the air currents is reduced. This has however, not always been easy, particularly in banks, where the machines are required on a constant basis close to a cashier's till.
As a reduction in operating speed and miscounting is undesirable anything that reduces the effect would be attractive solution to the purchaser and user of the machine. To some extent the problem has been mitigated by the arrangement described in our granted UK Patent GB-B-2 270 986.